The Tor Browser / file revision

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      http://creativecommons.org/publicdomain/zero/1.0/

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 <svg xmlns="http://www.w3.org/2000/svg" xmlns:xlink="http://www.w3.org/1999/xlink">

   <!-- From https://bugzilla.mozilla.org/show_bug.cgi?id=779029 -->

   <title>Test that the x/y/width/height attributes work on the mask element</title>

   <mask id="mask" x="20%" y="20%" width="60%" height="60%">

     <rect width="1000" height="1000" fill="white"/>

   </mask>

   <rect width="100%" height="100%" fill="lime"/>

   <rect x="50" y="50" width="100" height="100" fill="red" mask="url(#mask)"/>

   <rect x="70" y="70" width="60" height="60" fill="lime"/>

 </svg>